Method and apparatus for measuring buckle or center stretch in cold rolled steel strips



APPll 1944- R. B. BECKETT 2,347,454

METHOD AND APPARATUS FOR MEASURING BUCKLE 0R CENTER STRETCH IN COLD ROLLED STEEL STRIPS Filed Oct. 8, 1941 liwizl'ors FOAM/V 5. 556K577:

Patented 25, 1

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METHOD AND APPARATUS FOR MEASKNG BUGKLE 0R CENTER TRETCH KN @OLD RGLLED STEEL STRES Rollin B. Beckett, Par-ma, ()hio, assignor to The American Steel and Wire Company of New Jen say, a corporation of New Jersey In the production oi. steel strip for various purposes, including the production of the socalled slats for Venetian blinds, it is found to be desirable, in order to satisfy the demands of the manufacturers of such blinds, to produce the strip from which the slats of the blinds are made, to produce such strip with what is known as a buckle in the strip.

In order to produce such a buckle, the strip is worked in such a way that the central portion of the strip is stretched or elongated more than the sides and edges of the strip. This working, however, which may be performed in various ways, is not sufficient to be measured.

The presence of such center stretch in the strip results in an actual elongation of that portion of the strip which, in view of the unaltered condition of the sides and edges of the strip, produces a wavy condition of the center of the strip, the number and extent of the Waves depending upon the amount of working to which the central portion of the strip has been subiected.

In the fabrication of slats for Venetian blinds, the strips thus formed are passed through a plurality of rolls which form a crown" in the strip, one side of which is concave, while the other is convex, after the strip has been passed through these rolls. The strip is passed through these rolls in such a, manner that the edges of the 1 strip become stretched more than the central or crowned portion thereof, so that the buckled or wavy configuration of the strip is stretched out.

It will be understood that the strip from which I the slats are formed are very thin, they being on the order of from about 0.007 to about 0.012

It Will be 0bof this buckle is a requisite, since in the subse-' quent rolling of the strips into slats, where the crown is rolled into the strip, the sides of the strip are lengthened so that the extra length represented in the buckle is necessary in the center to allow the edges to be stretched or elongated to meet the length of the center, which results in a straight Venetian blind slat, that is devoid of any of the original buckle.

It is found that one accurate way of measuring the amount of the buckle present in a strip which has been worked so as to produce that buckle is to measure the amount of curvature or camber which results when such'a buckled strip is slit accurately along its center until the strip is divided.

When such a buckled strip is cut through ac-' curately along its center line, it is found that the resulting release of tension along the buckled center causes the severed parts of the strip to bend or bow edgeways, while lying fiat upon a table or other surface. The amount of this bending is determined by the amount of buckle inthe original strip. a

It will be seen, consequently, that one of the objects of the present invention is to provide a method and means. for the accurate measurement of the amount of buckle or center stretch in a thin steel strip that has been worked in such a way as to produce such a buckle or center, stretch.

Further objects of the invention will. become apparent as the description proceeds, and the features of novelty will be pointed out in greater particularity in the appended claims; audit will be understood that the specific embodiment of the invention described herein and illustrated in the accompanying drawing,.is illustrative only of the features of the invention and one mode of its application, the specific details of the in- I vention being subject to modifications and changes which may be necessary to adapt the invention to varying conditions and uses.

The invention will be understood more readily by reference to the accompanying drawing, wherein Figure 1 is a side elevation of a form of measuring apparatus intended to measure the depth facturers are being supplied, all of wh ch reof the curve or camber formed by the slitting of a buckled strip along the center thereof; Figure 2 is a top plan view of the apparatusof Figure 1; t

Figure 3 is a sectional elevation taken ou -the,

line III-III of Figure '1, looking in the direction of the arrows.

Referring more particularly to the drawing, the apparatus comprises a steel block which is provided withan upstanding flange I, the block 5 being recessed as shown at 9 to receive a measuring micrometer II, which is inserted through a hole I-3 in the flange I.

The top of the steel block I is smooth and is overlaid with a heavy plate l5, which preferably is made of glass, and serves a function which will be described hereinafter.

The test piece I! is laid between the glass plate It and the steel block I, the plate I! being cut away as indicated at It to provide clearance for the micrometer II.

In operation, a sample of the strip to be tested, which sample is long enough to overlap the ends 2| and 23, is slit as accurately as possible into two equal parts, along a line running exactly in the center of the strip lengthways, which will divide the strip into two equal parts. The exact length of the strip is not material, so long as it is long enough to overlap the ends 2| and 23 In the present instance, the buckle is not removed by a continuous rolling through succesof the block 5 since, with the edge of the test piece resting on the ends of the flange l, as shown in Figure 1, the flange I forms a chord of constant length,

When the sample of strip has been slit, either of the two resulting halves, one of which is the test piece II, will lie substantially flat when laid upon a flat surface such as the block 5. The

. plate l5 then is laid upon the test piece II, the

weight of the plate l5, coupled with the thinness of the piece H, which piece is shown in much exaggerated thickness in the drawing, completely flattens the piece,'which piece assumes a bend or camber 25, the test piece I! thus defining an arc of which the flange l is the chord,

and to which the micrometer II is perpendicular. The amount of this camber then is measured by means of the micrometer II, which enters the hole 13, and which is threaded in a collar 21 v which is mounted on the flange 1 and suitably secured thereto.

The amount of this camber depends upon theamount of strain which has been imparted to the center of the original strip by the center stretching thereof, Accordingly, this camber is a measure of the amount of buckle which had been worked into the original strip.

When it is desired to duplicate the amount of this buckle, a duplication of the amount of camber duplicates the amount of the buckle, There'- fore, it is possible to duplicate the original strip whenever desired.

It may be mentioned at this point that when in cold rolling of strip there is produced a buckle in the strip, as the strip is given further passes through successive stands of rolls, such further rolling is conducted so that the buckle will be removed. This operation, of course, takes place in the same plant, and the strip passes through the. successive roll stands simultaneously andcontinuously as the strip unwinds from the reel at one end of the roll stands-and winds on another reel at the other end of thestands, Thus,

the purpose is to produce strip that is free from sive stands of rolls, but the buckle remains in the strip until after shipping to the manufacturer of slats for Venetian blinds, the buckled strips are passed through the set of forming rolls which form the slat, and wherein the requisite "crown" is imparted to the slats. At the same time, the passing of the strip through the forming rolls completely removes the buckle from the strip as it is formed into a slat.

Therefore, it will be seen that, in accordance with the present invention, one of the important features of the improvements represented thereby resides in imparting to the strip a feature which generally is undesirable and must be removed from the strip if present, before the strip can be fabricated properly into desired articles to be made therefrom.

This usually objectionable feature is the buckle, which although for the great majority of uses of the strip is removed as the strip is rolled; in the present case is imparted purposely to the strip which is to be formed into blind slats, the presence of such buckle being a requisite for the satisfactory production of Venetian blind slats by the manufacturers thereof, who buy these purposely buckled strips which have been made for them,

Consequently, contrary to the usual practice of removing buckle continuously from the strip as the strip is rolled, in the case of the buckled strip comprising Venetian blind stock, the purposely produced buckle is left in the strip, which strip will be used in some location far distant from the mill which produced it, and at an indefinitely long time after it has been produced.

Therefore, in the production of this buckle in the strip, what is usually an unwanted and objectionable defect is converted into a desirable and requisite feature in Venetian blind stock and which, in accordance with the present inven tion, is utilized for the rapid duplication of succeeding strips which fulfill the specifications of slat manufacturers.

Also, contrary to the usual practice of removing any buckle immediately during the rolling of strip, for the present purpose the buckle is retained in the strip and is not removed therefromuntil the manufacturer of the slats for blinds passes the strip through the crowning rolls, which crown the strip and at the same time pull the sides and edges of the strip more than the center thereof, thus pulling out the buckle, and producing a finished slat which has been formed with a proper crown and which is free from buckle.

While a large number of Venetian blind slats are made from fiat strip stock that originally is free from buckle, nevertheless the present mechanical equipment of many manufacturers of slats for Venetian blinds will operate properly only on buckled stock in the production of the crown in the strip as it is formed into the slats, and consequently the buckled strips are necessary articles of commerce, and specifications vary as to the amount of buckle, some requiring deep, short waves while others require long, shallow waves.

Therefore, a mill which produces strips for Venetian blind manufacturers must not only supply such manufacturers with flat strip free from buckles, but must be prepared to duplicate on short notice any strip, either flat or with any type of buckle that may be required to fill satis- 2,347,454 factorily and speedily the orders which the manufacturers of the blinds may require.

The present invention provides a ready procedure and equipment to enable such duplication to be made readily and quickly at any time that such duplication may be required.

While the invention has been described specifically in connection with strips that are to be formed into slats for Venetian blinds, it is useful in connection with any use of the strips which requires a buckle therein.

It may be noted, also, in connection with the present invention, that the measure of the approximate camber of the test piece I! suflicient for all practical purposes would be, or is related to, the approximate variation of the arc of camber, which varies with the approximate trigonometric functions of the particular are in its variation, or formation from a straight line. This is on the assumption that the arc of camber is a portion of the circumference of a true, or approximate circle. However, in view of the very small values involved, any departure of the are from a portion of the circumference of atrue circle is insignificant.

In the measurement which is illustrated in the drawing, the height of the arc of camber 25 which is measured by the micrometer II, and of which the flange l is the chord, actually is the versine of one-half the angle subtended by the arc of the camber.

I claim:

1. Apparatus for measuring the amount of buckle in a steel strip, which comprises in combination, a block'having a substantially fiat surface, a plate for the block overlying the block and enabling a test piece of steel to be inserted between the plate and the fiat surface of the block, measuring means carried by the block, andmeans defining a chord for a cambered steel strip, the measuring means being positioned relative to the said chord to measure the amount of camber in the strip.

2. Apparatus for measuring the amount or buckle in a metal strip designed for a slat in a Venetian blind, which comprises, in combination, a block having a substantially flat surface for receiving the strip, a retaining plate for the block adapted to overlie the strip placed upon the fiat surface of the block, an upstanding flange extending longitudinally of the block, a measuring device carried by the flange for measuring the amount of camber in a cambered test piece placed upon the block between the block and plate, the said block and plate being suitably recessed to receive and accommodate the measuring means when manning the piece.

3. Apparatus for measuring the amount of buckle in a metal strip designed for a slat in a Venetian blind, which comprises, in combination, a block having a. substantially flat surface for receiving the strip, a transparent retaining plate overlying block adapted tohold a test piece in flat position on the flat surface of the block, while allowing the piece to assume an edgewise camber, and means for measuring the amount of the said camber, the means being carried by the block and positioned to engage the camber radially thereto.

4. Apparatus for measuring the amount of buckie'in a buckled metal strip, which comprises, in combination, instrumentaiities for receiving a test piece of the said strip and for maintaining the piece in flat position while allowing the piece to form a camber along the edge thereof, and means on the instrumentalities for measuring the amount of the camber,

thereby enabling the duplication of the amount.

of buckle in succeeding strips.

5. Apparatus for determining the amount of buckle in metal strips having a buckle produced therein, which comprises mounting means for receiving and mounting a test portion of the strip, which has been produced by cutting a piece of a buckled strip along its center line, the mounting means allowing the test portion to form a camber along its out edge, a flange on the mounting means defining a chord of the camber and measuring means associated with the mounting means for measuring the amount of the said camber, said measuring means comprising a micrometer gauge mounted in the said flange and extending radially of the camber for measuring depth of curvature of the said camber.

6. The method of determining a non-uniform or heterogeneous condition of strain in crystal structure of a metal strip extending transversely and longitudinally of the strip, which has been subjected to a workirg in mechanism adjusted to produce in the strip a heterogeneous transversely and longitudinally extending strain designed to form a succession of repeated cambered areas longitudinally of the strip, thereby forming a succession of areas of buckleperpendicular to the surface of the strip, to enable the duplication of the same or'similar heterogeneous strain conditions transversely and longitudinally of the strip ata subsequent time on another strip, and after the original adjustment of the heterogeneous transversely and longitudinally extending strain producing mechanism has been disturbed from its original adjusted setting so as to prevent duplication of the original strain in succeeding strip, which method consists in severing, by a uniform operation, a longitudinal section of. a selected test sample with a width and length enabling the heterogeneous transversely and longitudinally extending grain or crystal structure to form the said longitudinally severed section of the strip into an arc in a flat plane, and determining the degree of arc, which determination represents the original heterogeneous trans- I versely andlormitudinally strained condition of the strip;

7. The method of determining a non-uniform or heterogeneous condition of strain in crystal structure of a metal strip extending transversely and longitudinally of the strip, which strip has been subjected to a working in mechanism adjusted to produce in the strip a heterogeneous transversely and longitudinally extending strain designed to form. a'succession of repeated cambered areas longitudinally of the strip, thereby forming a succession of areas of buckle perpendicular to the surface of the strip, to enable duplication of the same, or similar, heterogeneous strain conditions transversely and longitudinally of the strip at a subsequent time on another strip, and after the original adjustment of the heterogeneous transversely and longitudinally extending strain producing mechanism has been disturbed from its original adjusted setting so as to prevent duplication of the original strain in succeeding strip, which method consists in severing by slitting by a uniform operation a longitudinal section of a selected test sample of the strip, restraining one of the said sections in flat position, the said section having a width and length enabling the heterogeneous transversely and longitudinally extending grain or crystal structure to form the said longitudinally severed section of the strip to form a camber along its strained edge, placing the said piece on a flanged gage block so that the flange of the gage block forms a chord for the camber, and measuring the amount of the camber, thereby determining the amount of buckle for duplication thereof in succeeding strips.

8. A method of grading strips of Venetian blind slat stock of the type wherein the strip is formed with a center stretch or buckle, which comprises slitting the strip along its center line to divide the strip into two equal parts, restraining one of the said parts in fiat position while allowing the part to form a camber along its strained edge, and measuring the amount of the camber, thereby determining the amount of buckle for duplication thereof in succeeding strips.

9. A method of grading strips of Venetian blind slat stock of the type wherein the strip is formed with a center stretch or buckle, which comprises slitting the strip longitudinally through the center thereof to form two equally sized pieces, restraining one of the said pieces in fiat position while allowing the piece to form a camber along an edge thereof, and measuring the amount of the said camber to determine the amount of buckle in the strip, thereby enabling duplication of the buckle in succeeding strips.

10. A method of grading strips of Venetian blind slat stock of the type wherein the strip is formed with a center stretch or buckle, which comprises cutting the strip along the stretched center line until the strip is divided into two substantially equal parts, allowing one of the parts to form a camber along its cut edge and measuring the amount of the camber to determine the amount of buckle in the original strip, thereby enabling ready duplication of the buckle in succeeding strips.

11. A method of grading metal strip:. of the type wherein the strip is formed with a center stretch or buckle therein, which comprises dividing the strip longitudinally through the buckle to form two pieces each having a buckled edge, restraining one of the said pieces in flat position while allowing the piece to form a camber along the buckled edge thereof, and measuring the amount of the said camber to determine the amount of buckle in the strip, thereby enabling duplication of the buckle in succeeding strips.

12. A method of grading metal strips of the type wherein the strip is formed with a center stretch or buckle, which comprises cutting the strip along the stretched portion thereof until the strip is divided into two parts, allowing one of the parts to form a camber along its cut edge, and measuring the amount of the camber to determine the amount of buckle in the original strip, thereby enabling ready duplication of the buckle in succeedingystrips.

ROLLIN B. BECKET'I. 

